The name helps of course — an ooh errr! gift for tabloid headline writers — as does her attractiveness, which won her affection among journalists.

But it is also her capacity for straight-talking, a readiness to go out on a bit of a limb, that makes Dame Suzi a source of interest.

Plenty of hot potatoes were thrown her way during her tenure as chairman of the Human Fertilisation and Embryology Authority [HFEA], and later as head of the School Food Trust, but she handled them with a deftness that has endeared her to ministers. Hence her appointment last year to the chairmanship of the Charity Commission.

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Now, however, this queen of the quangocracy, a self-proclaimed Christian Socialist, faces what could be her sternest test: taking on the might of the English public school system.

The commission, which oversees the activities of some 170,000 organisations in England and Wales, is to shine a light on the charitable status that allows independent schools to escape an estimated £100 million in tax.

Under the Charities Act 2006, schools such as Eton, which charges £26,500 per pupil per year plus extras, must show that they offer a "public benefit" not confined to an elite few.

What that means in practice will become clear early next year, but it will certainly not mean just turning over the sports field to boys from the local housing estate once a week.

Schools facing complaints under the Act will find themselves subject to investigation and possible withdrawal of charitable status.

The coming battle with the cradle of the Establishment appears to hold no fears for Dame Suzi.

"It's going to be a difficult and contested territory which will go inevitably to the charity tribunal. And I welcome that," she said.

Tony Little, the headmaster of Eton, says independent schools will be distracted from their main aim — teaching — by the demands of a "vast bureaucratic exercise".

Such comments are unlikely to deflect Dame Suzi. The Etons of this world, she warned earlier this year, will be subject to the same rules as any other charity. "They will have to show that they bring public benefit, including to people on low incomes," she said. "There's a level playing field for everyone now."

Defenders of charitable status for private schools, and private hospitals, accuse Gordon Brown of waging class war by proxy. If Labour wants to sock it to the upper classes, they argue, then let it do so openly, not through a supposedly non-political quango.

Dame Suzi is in a delicate position, made no less delicate by the fact that she is both a member of the Labour Party and the mother of a pupil at an independent school. The latter was cited by Dame Suzi as a "conflict of interest", justifying her absence from adjudications on the charitable status of individual schools.

But she cannot absent herself from overall policy. The heat will be turned up next spring when the country's 2,500 schools receive clearer information on their obligations.

Fee-charging schools may be in a minority, educating just seven per cent of children, but they tend to be an influential one. "I don't think you can take the politics out of the status of independent schools. I think there is sense in taking the party politics out of it," she offers. Tory-voting parents are unlikely to buy that line.

Still, Dame Suzi can cope. Born in colonial Uganda in 1956, her parents were both doctors. Her mother was also a psychosexual counsellor.

Privately educated before switching to sixth form at a comprehensive, she read politics at Exeter University and secured an MA from Leicester. She worked as a researcher for a consumer organisation before training as a probation officer.

Marriage to Iain Hampsher-Monk, a politics lecturer at Exeter, was followed by three children and a 10-year break from full-time work. That ended in 1997 with her appointment to the chairmanship of the Exeter and District NHS Trust.

She has been occupying chairs ever since, at the HFEA, the Food Standards Agency and the School Food Trust, set up after Jamie Oliver's assault on the Turkey Twizzler. While there, Dame Suzi lobbied for more money per pupil per school meal, accusing the Government of inadequate funding. Her legacy was the ban on schools selling sweets, crisps and fizzy drinks.

She has held 30 public appointments in the past 15 years, a record that failed to endear her to that champion of private enterprise, the Adam Smith Institute. It accused her of pursuing a "political agenda" on private education on behalf of politicians who lacked the "moral courage" to tackle the issue themselves.

Lord Winston, one of the pioneers of fertility treatment, was also not a fan of Dame Suzi. In 2004 he accused the HFEA of incompetence in its work of regulating fertility clinics and embryo research. The body was, he alleged, overly bureaucratic and an obstacle to scientific progress.

But her personal reviews are generally favourable, with a former colleague at the HFEA describing her as receptive and unassuming. "When people reach her status they start thinking 'I'm important, I don't have to listen'. Suzi was never like that."

She is also, according to Geraldine Peacock, her predecessor at the Charity Commission, rather good at foot massage.

But if political hatchet work is needed, Dame Suzi has the tools. She can deploy humour and charm (wearing leather — get it — at press events) and was not afraid of taking on the medical and scientific community over developments in fertility research.

While at the HFEA she gained a reputation for tackling sensitive issues head-on, gaining the respect of patients. She made a number of controversial statements, including: "There is more to life than having children", while backing IVF for lesbian couples.

She also displayed a willingness to draw blood, sacking the HFEA's chief executive, Dr Maureen Dalziel.

At 51, Dame Suzi has managed the enviable feat of combining a successful career in public life with raising three children. Her endeavours on behalf of New Labour earned her a DBE in the 2006 New Year's Honours List.

Explaining the secret of her success, she advised: "Choose your husband extremely carefully. A lot of the glass ceiling is at home."